Coriolis lists the protection from 3 MRPs as 94%.
So my understanding of all of the above is that you stack the bottom two Class 1 slots with MRPs and one upper Large Class Size slot with another MRP.
That way 94% of damage that should have gone through to a module will be soaked up by the Biggest MRP.
By the time the Big MRP is gone, you should be just about waked out of there with a couple of percent of Hull left. You never want to be relying on those tiny MRPs so if you get any module failures you need to be watching that FSD charging bar.
I run a shieldless frag Krait and it rocks my box.
Reactive Armour with G5 Thermal Resist and Deep Plating
5 HRPs all G5 Heavy Duty with Deep Plating.
3 MRPs
All internals and Utilities Engineered either for cold or for integrity. Sometimes even B rated for more base integrity.
Idles at 22% thermal. And has like a kabillion hit points. Handles like a brick and hits you like one.
The sheildless thing makes CMDRs think I'm easy prey.
My favorite thing is when we've been jousting a while and they can see I'm kinda slow, my opponent is on about 40% hull and I'm on about 32% and they try their first ram.
Suddenly they're 24% and I'm 29% and they're sitting still within easy reach of my Frags, with seconds to go until their next boost is available. Because of shieldless I can keep 4 pips to engines and perma boost, only swinging pips to weaps if they're coming in slow enough that I can get a second round of frags off with the fast reload from the Double Shot Screening Shell.
In a long fight I do a lot of toggling the silent running, but my PAs also have Target Lock Breakers so I'm kinda super annoying to fight. "Where'd he go?"
And then I have so many hit points that if I feel like I'm going to die, I have time to wake out.
I was in a CZ with a buddy the other day and he said I was entertaining because I barge around smashing into things. Going nose to nose with a vette pips to weaps spray spray spray.
And yeah - when you hull tank - your hull is your ammo.
PvP - wake out for repairs at 17% remaining.
PvE - As long as there's no Spec Ops around you can run it down to 3% before looking for your exit. But I have taken a few rebuys from thinking I'm bulletproof.